The present disclosure relates generally to semiconductor device manufacturing techniques and, more particularly, to doping of copper wiring structures in back end of line (BEOL) processing.
Integrated circuits are typically fabricated with multiple levels of patterned metallization lines, which are electrically separated from one another by interlayer dielectrics containing vias at selected locations, to provide electrical connections between levels of the patterned metallization lines. In recent years, copper (Cu) has replaced aluminum (Al) as the metal of choice for wiring of microelectronic devices, such as microprocessors and memories. However, copper has a tendency to diffuse through insulators, such as silicon dioxide, during high temperature processes. As a result, the use of copper wiring also necessitates the placement of efficient diffusion barriers surrounding the copper wires, thereby keeping the copper atoms confined to the intended wiring locations and preventing circuit malfunctions, such as shorts.
As electronic devices become smaller, there is also a continuing desire in the electronics industry to increase the circuit density in electronic components, e.g., integrated circuits, circuit boards, multi-chip modules, chip test devices, and the like, without degrading electrical performance, e.g., without introducing cross-talk capacitive coupling between wires while at the same time increasing speed or signal propagation of these components. One method for accomplishing these goals is to reduce the dielectric constant of the dielectric material in which the wires are embedded. Toward this end, a new class of low dielectric constant (low-K) materials has been created. Low-K interlevel dielectric (ILD) materials are advantageous so long as device reliability is not compromised. However, the lower the dielectric constant of the low-K dielectric material, the more challenging the integration becomes. For example, low-K generally corresponds to lower modulus, lower thermal conductivity, increased porosity, and greater susceptibility to plasma damage, in turn leading to lower reliability.